I. Field of the Invention
The present invention relates to a reflector and a method for manufacturing the same and, more particularly, to an aluminum reflector which has good resistance to corrosion and a method for manufacturing the same.
II. Description of the Prior Art
An aluminum reflector is conventionally used for a reflecting shade for illumination, a parabolic reflector and the like. This aluminum reflector is constituted by an aluminum reflecting layer supported by a base body made of, for example, aluminum. The aluminum reflecting layer is generally coated with a light-transmitting inorganic oxide layer in order to prevent it from being degraded by the outer atmosphere.
The aluminum reflector of this type has advantages of good hardness, resistance to abrasion, oil resistance, heat resistance and the like by the presence of the light-transmitting inorganic oxide layer. However, this aluminum reflector does not have good resistance to chemicals. Therefore, the aluminum reflector is degraded by carbon dioxide, nitrogen monoxide, nitrogen dioxide, sulfurous acid gas, ammonia or the like which are contained in the air, so that the aluminum reflector may not be used with a desired performance for a long period of time.
The conventional aluminum reflector has another drawback in that the aluminum constituting the reflecting layer and the base body may be dissolved and corroded when the reflector is immersed into an electrolyte solution together with a metal which has a substantially higher ionization tendency, although when present alone in the electrolyte solution, the reflector may not be dissolved and corroded. Therefore, if the base body is made of a metallic material having an ionization potential substantially higher than that of aluminum, the aluminum reflecting layer is corroded and dissolved even when the reflector is present alone in an electrolyte solution.